Home solar nets $1,000 worth of “gas” in 81 days

In just 81 days with a 5.59 kW home solar system, we’ve produced 1,679 kWh more than we’ve used. And, thanks to our utility’s indefinite kWh rollover option – an option which, to be truthful, I’m not sure how many other electric utilities in the U.S. offer — we’ve banked these extra kWh hours as fuel for a future electric car.

Add the $85 of electricity we’ve used to power our home in the last 81 days to the $1,007 in “gasoline” savings we’ve amassed so far, and we’ve generated nearly $1,100 worth of savings — in less than three months!

Of course, the out-of-pocket costs for our 5.59 kW solar system were $8,500, which means we’ve got $7,400 to go before we break even.

Break-even point = 3 ½ yearsBut our break-even point is going to come soon. In fact, thanks to the fact that our solar system is acting not only as a home electricity provider but as an auto-fueling system, this break-even point is going to come far sooner than it would have in a traditional solar payback situation in which payback is calculated based on the home electricity savings only.

At the current rate, we’ll hit payback for our solar system in approximately 3 ½ years — and that’s not even accounting for inflation in electricity rates or gasoline. After that, we’ll be pumping free sunlight generated electricity into our electric car for 20 or more years – this while electricity rates and gasoline costs continue to go up, up, up.

Here are numbers I’m using to calculate the $1,000 in gasoline savings we’ve generated so far, as well as for the long-term solar system payback projections:

$3 per gallon of gasoline

20 m.p.g.

1 kWh = 4 EV miles

If you increase the miles per gallon average, our current savings picture isn’t quite so dramatic. But it’s still very good. At 30 m.p.g., in the last 81 days, we’ve amassed $672 worth of “gasoline” savings via our home solar system. At 40 m.p.g., we’re at $503 of “gasoline” savings. And even when we plug a whopping 50 m.p.g. into our equation, our savings still come in at $403!

Banking Sun Miles™ for the futureIt’s worth crunching the numbers in the other direction as well. Gasoline prices are far higher in much of Europe and Asia than they are in the U.S. Furthermore, gasoline prices in the U.S., and elsewhere, are sure to rise between now and the approximately 1 ½ years we’ll be banking future Sun Miles™ before we’ll be able to purchase an electric car here in Colorado.

For example, let’s assume a per gallon cost of $5 and 20 m.p.g. With these figures, in just 81 days of using our home solar system to generate and bank kWh to power a future EV, we’ve amassed $1,679 worth of “gasoline” savings.

So much for claims that solar is “too expensive”.

To the contrary, if you use your home solar system to power your home and a future electric car, you’re going to save money on fueling costs — potentially quite a lot of money — as our individual case clearly illustrates.

Like this story? Interested in the solar EV/PHEV synergy? Join our Sun Miles™ Cluband start meeting & interacting with other people around the world who want to drive, or already are driving, their cars on sun! Register to join us today!

About The Author

Christof Demont-Heinrich is founder, creator and editor of SolarChargedDriving.Com, which he launched in September 2009. A journalism professor at the University of Denver (DU), Demont-Heinrich is a lifelong environmentalist who loves to bird, hike, camp, and bike. As passionate as he is about the environment -- and about promoting the synergy between solar power and electric cars, he is equally passionate about writing.